Which meteorites rarely reach Earth?空投盗U反检测

April 15, 2025  21:25

Carbonaceous meteorites, despite being abundant in space, make up less than 5% of meteorites found on Earth. These objects are scientific treasures, packed with organic compounds, amino acids, and water—potential building blocks of life. Yet, they rarely survive the journey to our planet’s surface.

Why Are They So Rare? The Sun and Atmosphere as Filters

An international team, whose study appeared in Nature Astronomy, analyzed 8,500 meteor events across 19 observation networks in 39 countries. They found that carbonaceous meteoroids—the precursors to these meteorites—are destroyed by two major forces:

1. Solar Heating: Fragile carbonaceous meteoroids endure repeated roasting as they orbit closer to the Sun, causing them to fragment or disintegrate in space before reaching Earth’s atmosphere.
2. Earth’s Atmosphere: Even if they make it to our atmosphere, their brittle structure buckles under intense heat and pressure during entry, burning up or shattering into tiny particles.

As Dr. Hadrien Devillepoix from Curtin University put it, the Sun and atmosphere act like “giant filters” that obliterate these materials.

Which Meteorites Don’t Make It?

The study highlights that carbonaceous meteoroids, particularly fragile, carbon-rich types like CI and CM chondrites, almost never reach Earth as meteorites. They either crumble under solar radiation in space or disintegrate in the atmosphere due to their low durability. In contrast, sturdier meteorites—like iron or stony ordinary chondrites—more often survive the atmospheric gauntlet to land on the surface.

Why It Matters for Science

This explains why carbonaceous meteorites are so scarce in researchers’ collections, despite their cosmic abundance. The findings carry big implications:

• Asteroid Missions: Understanding these materials’ fragility will guide future sample-return missions to asteroids.
• Origins of Life: Carbonaceous meteorites may have delivered water and organics to Earth, but their rarity prompts a rethink of how these ingredients arrived.
• Risk Assessment: Knowing how brittle meteoroids behave could sharpen predictions of meteorite hazards.

The Bottom Line

Carbonaceous meteorites rarely reach Earth because their delicate nature can’t withstand the Sun’s heat or our atmosphere’s fiery barrier. Every specimen that does land is a priceless clue to the cosmos, making them all the more valuable to science.